MEXICO CITY - Despite sunny skies and hot weather, Prime Minister Stephen Harper may not get the warmest reception during his first official visit to Mexico.

Though Mexican officials have hinted that tensions over a visa imposed in 2009 by the Canadian government will not overtake the week's events, the issue has also been a roadblock to increased economic co-operation between the two countries - exactly what this trip is intended to foster.

Harper will spent two days in Mexico City for bilateral trade talks with Mexican President Enrique Pena Nieto before they are joined by American President Barack Obama for the North American Leaders' Summit in Toluca.

Officially on the agenda for the bilateral program is increased economic integration and energy co-operation between Canada and Mexico.

Mexico is among the world's fastest emerging markets, enjoying a recent boon in both its manufacturing and energy sectors. Mexico is eagerly developing its significant shale gas reserves and it wants access to Canadian expertise.

In a statement released prior to the trip, Harper calls Mexico "one of Canada's closest friends partners" and hailed "70 years of excellent diplomatic relations."

Those statements mask a growing resentment among Mexican officials that Canada hasn't done enough to nurture the relationship.

Earlier Monday, the Canadian Press reported that the federal cabinet has given Trade Minister Ed Fast its blessing to sign an expanded airline access deal with Mexico - potentially a precursor to any deal that would see the visa requirement lifted altogether.

The deal includes giving greater access to Mexican airlines to Canadian cities, as well as more direct flights for Canadians to Mexico.

It was reported last week that Mexico's ambassador to Canada, Francisco Suarez, wanted more flights from Mexico to Calgary, specifically to learn from Canadian experts in the oil and gas industry.

When the visa was imposed in 2009, a large number of Mexicans were arriving in Canada to claim asylum.

The government has explained the visa as a means of protecting the integrity of the Canadian immigration system. Since then, the number of Mexicans travelling to Canada has been roughly halved.

Mexico calls the visa a hindrance to trade and has pushed Canada to remove it. Harper imposed a similar visa on citizens of the Czech Republic also in 2009, though that visa has since been lifted.

Ahead of the visit, Canadian officials assured no deal on the visa issue will be announced this week.

Harper, Nieto and Obama will sit down Wednesday to talk "economic competitiveness, energy and the environment," according to the Prime Minister's Office.

One thing that won't be discussed here is the proposed Keystone XL pipeline to ship Alberta crude to Texas refineries.

Harper has been vocal in calling on the Americans to approve it or not.

American officials have let it be known they will not be rushed into a decision by Canada and said when their process has been completed and a decision made, Canada will be made aware.